2
Problem Statement in Draft Site-locals not globally unique Sites cannot be “merged” without first renumbering –Renumbering eventually necessary, but over time Site-local address is potentially ambiguous outside immediate context of network layer –In email or a file

4
Solution in Draft Don’t use a registry –Even registry can’t enforce uniqueness –Because of site splits Instead each site choose a random number –Literally toss coins –Or, ISP can assign random number from good random number generator

5
Low probability of collision For any given site, very low probability that it will ever connect to another site with same prefix –Some math errors in the draft, off by maybe factor of 2 –Conclusion still applies

6
Draft Error Near-unique site-locals don’t really help with merging sites If two merged site halves maintain separate global prefixes –Advertise prefix to each half If two merged site halves obtain same global prefixes –Must renumber anyway (near-unique or not)

17
Discussion? Benefit not as strong as draft states Still there is some benefit Picking random number is easy, doesn’t require change to implementations –Seems no good reason to disallow a site from doing it Picking a random number is kind of weird